1. Technical Field
The present invention relates to a display panel, such as an organic EL panel, to a display device, and to a display module of a movable body.
2. Related Art
In recent years, an organic EL panel using an organic electroluminescent (hereinafter, referred to as ‘EL’) element has been drawing attention in that it is better than other devices due to the low power consumption, a wide viewing angle, and a high contrast ratio thereof. As an example of the organic EL display device using the organic EL panel, JP-A-2004-127924 discloses an electronic module in which an organic EL panel and a flexible wiring substrate connected to the organic EL panel are included and in which a driver IC is mounted on the flexible wiring substrate and an organic EL element located at each of a plurality of pixels is driven by the driver IC (See FIG. 14 in JP-A-2004-127924). In the organic EL display device of the related art, a data line pad serving as a connection terminal part for a plurality of data lines and a power supply line pad serving as a connection terminal part for a plurality of power supply lines are disposed in a single horizontal line on a light-emitting element substrate of the organic EL panel.
In a liquid crystal display device of which the drive principle is different from that of the organic EL display device, it is not necessary to supply a driving current to liquid crystal provided at each pixel, and thus the number of terminals for power supply decreases. Specifically, since it is sufficient to supply a current having an intensity of several tens of milliampere to a gate of a thin film transistor (TFT) provided at each pixel and to provide one power supply line or several power supply lines on an element substrate of a liquid crystal panel, it is possible to realize an arrangement in which one or several power supply lines are located between signal lines. That is, it is possible to form a terminal of the one power supply line or terminals of several power supply lines between signal lines, on the same pad as terminals of a plurality of signal lines are formed.
In contrast, in the organic EL display device disclosed in JP-A-2004-127924, it is necessary to supply a current having an intensity of several ampere, for example, one to two ampere, to the organic EL element of each pixel while the organic EL element emits light. In order to supply such a large current to the organic EL element of each pixel, a plurality of power supply lines for supplying the power to each pixel circuit needs to be provided on the light-emitting element substrate of the organic EL panel. In reality, the power supply lines connected to each pixel circuit are thick strip-shaped power supply lines provided individually for each pixel of R (red), G (green), and B (blue), and the total number of power supply lines is 20 to 30 for each pixel of R, G, and B (20 to 30×3) and a ground line (1). As such, in the organic EL display device, four kinds of power supply lines, which are the power supply lines for each pixel of R, G, and B, and the ground line, are needed. In addition, it is necessary to provide 20 to 30 power supply lines or one thick strip-shaped power supply line for each pixel of R, G, and B.
However, in the organic EL display device of the related art disclosed in JP-A-2004-127924, when the data line pad and the power supply line pad of the organic EL panel are electrically connected to a terminal part of the flexible wiring substrate, an adhesive with an anisotropic conductive film is attached onto each of the pads and the terminal part of the flexible wiring substrate is thermally pressed onto each of the pads with the adhesive with the anisotropic conductive film interposed therebetween. For the pitch between terminals (width between the centers of terminals) in the connection terminal parts, such as the data line pad or the power supply line pad, 40 to 60 μm is a mounting limit of the terminals that are typically mounted. The pitch of 40 to 60 μm is the pitch limit in the manufacturing technology when the position deviation of terminals during the thermal pressing is considered. As in the organic EL display device of the related art, in the configuration in which the data line pad and the power supply line pad are disposed in the single horizontal line, for example, in an organic EL display device having a high resolution of 128 ppi, a plurality of data lines are densely provided, whereby it is difficult to dispose a plurality of power supply lines among the plurality of data lines. Further, the higher the resolution of the organic EL panel of the organic EL display device, the narrower the pitch between data line pads (data line pad pitch), as shown by a curve 600 on the graph in FIG. 12. In the graph, the horizontal axis corresponds to the resolution of the organic EL panel (OLED panel resolution), and the vertical axis corresponds to the pitch between data line pads. Furthermore, as the brightness of the organic EL panel is higher, it is necessary to supply a larger current to the organic EL element. Accordingly, it is necessary to make thicker the thick strip-shaped power supply line provided at each pixel of R, G, and B.
As such, the higher the resolution and the brightness of the organic EL panel, the higher in difficulty to dispose the plurality of power supply lines among the plurality of data lines. In addition, since there is the mounting limit in the terminals to be mounted, there has been problems in that the ratio of a display area to the panel size in the direction where a plurality of data lines are disposed is small and a non-display area, that is, a frame portion is large. These problems are not limited to the organic EL display device but affect a display panel using a self-luminous light-emitting element.